Nerve Impulse Transmission and Nervous System Evolution
Transmission of Nerve Impulses from Neuron to Effector Organs
The transmission of nerve impulses to effector organs is conducted similarly to what happens at the synapse. Neurotransmitters are released into the effector organs. Thus, effectors respond to the presence of the neurotransmitter, causing a muscle to contract or producing a secretion in the case of a gland.
Invertebrate Nervous System
As one ascends the evolutionary scale, the nervous system acquires greater complexity:
- It tends to direct
Ecosystems and Living Organisms: Interactions and Adaptations
Understanding Ecosystems and Their Components
All living things that inhabit our planet belong to a species. Individuals of the same species can breed with each other and produce fertile offspring. Individuals of the same species living in the same area form a population. The set of populations that share a territory and establish relationships with each other is called a community or biocenosis. The territory occupied by a biocenosis, which has specific physical and climatic characteristics, is
Read MoreCellular Reproduction and Biological Development: A Comprehensive Study
**Asexual Reproduction**
- Occurred 3500 million years ago
- Involves mitosis
- One progenitor
- Normal cells
- Simple and profitable reproduction system
- Genetically identical individuals
- Recombination of genes, not characters
- Rapid growth in the number of individuals
**Sexual Reproduction**
- Occurred 1500 million years ago
- Involves meiosis
- Almost always two parents
- Special cells
- Constructive and very complicated reproductive expenditure
- Genetically different individuals
- Easy recombination of genes and characters
**Parthenogenesis*
Read MoreCarbohydrate Classification, Properties, and Functions
Carbohydrate Classification
Monosaccharides (Oses)
Classified according to the functional group:
- Aldose
- Ketose
Based on the number of carbon atoms:
- Trioses (3)
- Tetroses
- Pentoses
- Hexoses
- Heptoses
Osids
- Holosids
- Oligosaccharides
- Polysaccharides
- Homopolysaccharides
- Heteropolysaccharides
- Heterosids
Carbohydrate Definition
Carbohydrates are compounds resulting from replacing one of the functional groups (-OH) of a polyalcohol with another functional group, either an aldehyde or a ketone.
General Characteristics of Carbohydrates
Carbohydrates,
Read MoreInvertebrate Animals: Sponges to Insects
Porifera and Coelenterata
Porifera, such as sponges, and Coelenterata, such as jellyfish and polyps, were once thought to be plants because they are often found fixed to a rocky or sandy substrate.
Porifera (Sponges)
The body of a sponge is shaped like a bag and is perforated by numerous pores, which communicate through its interior canals. The main cavity communicates with the outside through a hole called the osculum.
Coelenterates
- Medusa: Umbrella-shaped with an opening at the bottom. They live floating
Eukaryotic Cells: Structures and Functions
Mitochondria
Mitochondria are organelles surrounded by two membranes, present in all eukaryotic cells. They are considered the power plants of the cell since they are the site of the oxidation of fatty acids and the aerobic phase of cellular respiration.
- Outer membrane: Smooth and permeable.
- External chamber: Located between the two membranes, with a composition very similar to the cytosol because of the permeability of the outer membrane.
- Internal membrane: Presents a series of folds directed toward